RAPD MARKER ESTIMATION OF GENETIC-STRUCTURE AMONG ISOLATED NORTHERN LEOPARD FROG POPULATIONS IN THE SOUTH-WESTERN USA

Amphibians in the south-western United States are currently experienci ng population declines. Causal explanations for these population chang es as well as the implementation of sound management practices require s an understanding of the genetic structure of natural amphibian popul ations. To this end, we estimated genetic differences within and among seven isolated populations of northern leopard frogs, Rana pipiens, f rom Arizona and southern Utah using random amplified polymorphic DNA ( RAPD) analyses. Fourteen arbitrarily designed primers detected 38 poly morphic loci in 85 individual frogs. Three types of population structu re were observed in this study. (i) Two populations showed low genetic diversity (D = 0.10 and 0.04) and may have been established by relati vely recent events. (ii) Two were not genetically distinct and exhibit ed a high degree of within-population diversity (D = 0.35). The possib ility of gene flow between these populations is high due to their geog raphical proximity and their shared genetic structure. (iii) Three pop ulations were genetically distinct from each other and the other popul ations, and exhibited intermediate within-population variation (D = 0. 19, 0.17, 0.14). Genetic distances among the seven populations ranged from 0.00 to 0.20, suggesting that some of these leopard frog populati ons are genetically distinct. Although based on relatively small sampl es, these data suggest that leopard frog populations in the south-west are likely to represent unique genetic entities worthy of conservatio n. The management implications of these results are that isolated leop ard frog populations should be evaluated on an individual basis to bes t preserve them.